Looks like turning flight/accelerated stall but some of the helo guys will chime in here for sure and give their expert opinions.

Quoted from another thread about this:
This will be a technical rant, so unless you are curious as to the cause of the crash skip all of this...

As a UH-60 pilot, a couple of observations.

First: that guy is demanding a REDICULOUS ammount of power from a single engine helicopter. Since this was filmed in the desert and, as such, it is probably very hot, you must expect reduced engine performance and lift production. Also note they have weapons stores installed which, even if dummy, add weight. So, recap: HOT and HEAVY.

Second: watch the freeze frame when the Z06 crosses the finish line and look at the windsock in the background. Looks like ~15 Knots of wind assuming the standard, 10 knot per ring windsock. If I counted my turn-arrounds correct, the Cobra had a tailwind when he crashed.

Prior to the crash sequence, the pilot made a max power takeoff followed by a sharp right turn right before he lost control. Note the hesitation 3/4 of the way though the turn which results in the crash. While it normally affects left turns, I think he got into LTE from a right quatering tailwind, more specifically the weathercock stability portion of loss of tail rotor effectiveness, tried to correct with left pedal but did not have enough power to get out of it, remember hot and heavy from before, and "drooped the rotor" leading to the crash.

That is a lot of fancy pilot speak, but that is also why U.S. Army flight school takes almost two years to complete and you typically fly for another 2~3 before you make Pilot-in-Command. That pilot was flying beyond the power margins of the aircraft and, if he was a U.S. Army pilot, he would most likely loose his wings for reckless flying. I have over twice the HP avaliable, ~3200, and a much more modern, 4 bladed rotor system, and there is no way in HELL I would do those kind of manuevers that close to the ground. No way....